CROSS-REFERENCE TO RELATED APPLICATIONS

This Patent Appl ication claims priority from Italian Patent Application No . 102022000018048 filed on September 2 , 2022 , the entire disclosure of which is incorporated herein by reference .

FIELD OF THE ART

The present invention relates to the field of manufacturing ceramic products , such as tiles , ceramic slabs , tableware , sanitary ware , etc . In particular, the present invention is in the field of processing a water suspension of ceramic material , also known as slip, in order to obtain atomised ceramic powder .

BACKGROUND OF THE INVENTION

In this field, it has been known for many years to produce atomised ceramic powder using spray-dryers . In detail , a spray-dryer used for this purpose typically comprises a main body defining a spray-drying chamber within which the aforementioned water suspension of ceramic material ( the so-called slip ) is processed in order to obtain atomised ceramic powder, which is then sieved and stored in special storage silos , from where it is taken to be used after a curing time such as to allow the even distribution of moisture and temperature values between the granules of this atomised ceramic powder .

More speci fically, the spray-dryer comprises : a feeding system configured to feed j ets of a water suspension of ceramic material at a high pressure into the spray-drying chamber by means of a plurality of noz zles , a hot air distributor placed at the top of the spray-drying chamber and configured to receive a flow of hot air from a heating assembly, typically formed by at least one burner, and distribute said flow of hot air into the spray-drying chamber according to determined paths , e . g . by causing the hot air to move in a swirling motion, so that the water suspension of ceramic material , atomised by the noz zles , and the flow of hot air, suitably distributed, upon meeting, lead to the formation of atomised ceramic powder and discharge fumes , intended to be introduced into the atmosphere through a discharge chimney after being suitably filtered and/or abated, e . g . by means of separating cyclones , abating bag filters , etc . so as to separate them from the ceramic material residues . On the other hand, the atomised ceramic powder, once dried, precipitates downwards and is discharged via a discharge belt .

The above-described spray-drying process , while of fering excellent performance , has some drawbacks , mainly environmental and energy-related, including the following .

The above-described spray-drying process involves a high consumption of water ; in fact, as mentioned above , when the process is complete , the discharge fumes , mainly consisting of water vapour, are dispersed into the atmosphere by means of special chimneys . It i s clear that the dispersion of these discharge fumes into the atmosphere , in addition to creating problems of visual pollution, mainly due to the fact that these discharge fumes escape at high temperatures and as soon as they are in the atmosphere they tend to condense , assuming a whitish colour that makes them well visible , also causes the dispersion into the environment , and therefore the waste , of a considerable quantity of water at each spray-drying cycle . In fact , much of the water used to form the aforementioned water suspension is totally dispersed into the external environment . This waste of water is a problem from an economic, but above all ecological and environmental perspective . In addition, the increasing drought problems of the recent years lead us to think that the issues related to poor availability of water which today af fect only certain areas of the planet and/or certain periods of the year could, i f not properly addressed in a short time , af fect increasingly larger areas for longer periods of the year .

DISCLOSURE OF THE INVENTION

The obj ect of the present invention is to provide a method and a system to recover water from a spray-dryer that allow to at least partially overcome the limitations of the prior art , by reducing the waste of water in known spraydrying plants .

In accordance with the present invention, a recovery method and system to recover water from a spray-dryer are provided as claimed in the independent claims below, and preferably, in any one of the claims depending directly or indirectly on the independent claims .

The claims describe preferred embodiments of the present invention forming an integral part of the present disclosure .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is hereinafter described with reference to the accompanying drawings , which show some non-limiting embodiments thereof , wherein :

- Figure 1 shows a schematic view of a water recovery system to recover water from a spray-dryer, in accordance with a first embodiment of the present invention;

- Figure 2 shows a schematic view of a water recovery system to recover water from a spray-dryer, in accordance with a second embodiment of the present invention;

Figure 3 shows a perspective view of a pos sible embodiment of the heat exchangers schematically shown in Figures 1 and 2 ;

- Figure 4 is a perspective view of a heat exchange module that is part of the heat exchangers in Figure 3 ;

- Figure 5 shows , on an enlarged scale , a side view of a possible embodiment of the cooling assembly of the recovery system in Figure 1 ; and

- Figure 6 shows a perspective view in an enlarged scale of part of the cooling assembly, schematically shown in Figure 2 ;

- Figure 7 is a perspective view in an enlarged scale of the heating device to heat slip, schematically shown in Figure 2 ; and

- Figure 8 is a schematic view of a part of the heating device to heat the slip, schematically shown in Figure 1 .

PREFERRED EMBODIMENTS OF THE INVENTION

In the attached figures , number 1 denotes as a whole a water recovery system to recover water from a spray-dryer 2 .

In the enclosed figures , the same numbers and the same reference letters in the figures identi fy the same elements or components with the same function .

In the context of the present disclosure , the term " second" element does not imply the presence of a " first" element . These terms are in fact used as labels to improve clarity and should not be understood in a limiting way .

The elements and features shown in the various preferred embodiments , including the drawings , may be combined with each other without thereby departing from the scope of protection of the present application as described below .

Referring in particular to Figures 1 and 2 , the recovery system 1 comprises a spray-dryer 2 , known in itsel f , configured to generate atomised ceramic powder AP from a water suspension of ceramic material , producing discharge fumes (not visible in the attached figures ) . In detail , advantageously but not limitatively, said water suspension of ceramic material , also known as slip, comprises ( in particular, consi sts of ) about one-third by weight of water and the remaining part ( therefore about two-thirds by weight ) of ceramic material , in particular comprising clays , sands and/or feldspars , etc . Furthermore, advantageous ly but not limitatively, such discharge fumes exiting the spray-dryer 2 have a temperature ranging from circa 80 ° C, in particular circa 85 ° C, to circa 115 ° C ; in particular, circa 100 ° C .

Even more advantageously but not limitatively, the discharge fumes obtained from the spray-dryer 2 of such a water suspension of ceramic material comprise from circa 100g, in particular circa 120g, to circa 170g, in particular circa 190g, of water vapour per kilogram of dry air and at most about 40 mg/Nm ³ , in particular circa 30mg/Nm ³ , of solid material ( in particular dust ) .

Advantageously but not limitatively, the spray-dryer 2 comprises , in turn : a main body 3 , preferably cylindrical , delimiting a spray-drying chamber 4 within which the spraydrying process takes place ; a feeding system 5 configured to feed the water suspension of ceramic material , in particular to feed j ets of such a water suspension of ceramic material at high pressure within the spray-drying chamber 4 ; a heating assembly 6 , to generate a flow of hot air, a distribution device 7 to distribute said flow o f hot air inside the spraydrying chamber 4 so that the flow of hot air hits the j ets of water suspension of ceramic material generating atomised ceramic powder AP and discharge fumes , advantageously but not limitatively of the type described above . According to some advantageous but non-limiting embodiments , the system 5 for feeding the water suspension of ceramic material comprises a tank 8 , wherein the water suspension of ceramic material is stored, and a pumping unit 9 , e . g . comprising one or more piston pumps that can be driven to take the water suspension of ceramic material from the tank 8 and introduce it at a high pressure into the spray-drying chamber 4 .

According to certain advantageous but non-limiting embodiments , the feeding system 5 comprises a plurality of noz zles (not visible in the appended Figures ) arranged within the spray-drying chamber 4 , advantageously but not limitatively along a crown concentric to the spray-drying chamber 4 or alternatively arranged on a plurality of bars cantilevered to an inner wall of the main body 3 so as to extend towards the inside of the spray-drying chamber 4 , which noz zles are configured to spray high pressure j ets of a water suspension of ceramic material into the spray-drying chamber 4 . Even more advantageously but not limitatively, such noz zles are oriented so that the respective j ets are substantially vertical and directed upwards ( in particular, towards the upper portion of spray-drying chamber 4 ) . Alternatively or in combination, according to some nonlimiting embodiments , the feeding system 5 also comprises safety filters 10 to filter the water suspension of ceramic material before it is fed into the spray-drying chamber 4 .

According to still other embodiments that will be better explained below, the recovery system 1 comprises a heating device 34 , 340 configured to heat the water suspension of ceramic material to a temperature of at least circa 70 ° C before introducing it into said spray-drying chamber 4 .

Advantageously but not limitatively, the heating assembly 6 compri ses at least one burner 11 , of a known type , for example methane gas or LEG or liquid fuel , and a pressurisation fan 12 configured to draw in ambient air and push it towards the burner 11 so that the latter can heat the air generating a flow of hot air, which reaches , through a supply duct 13 , the aforementioned distribution device 7 , which advantageously, but not limitatively, has an annular shape and is configured to impart a controlled swirling motion to the aforementioned flow of hot air, so that the water suspension of ceramic material , nebulised by the aforementioned no z zles and the suitably distributed flow of hot air, upon meeting, cause the formation of atomised ceramic powder AP, which, once dried, precipitates towards the bottom of the spray-drying chamber 4 and is discharged via a discharge belt 14 , and of discharge fumes which are conveyed towards the outside of the spray-dryer 2 itsel f .

Advantageously but not limitatively, the spray-dryer 2 also comprises an expulsion system 16 configured to convey such discharge fumes out of the spray-dryer 2 , and to filter and/or abate them . According to some advantageous but nonlimiting embodiments , such an expulsion system 16 comprises at least one sucker fan (not shown) that draws in such fumes and filtering and/or abatement devices 17 , such as a bag filter, to filter such discharge fumes .

Advantageously, the recovery system 1 further comprises , at least one duct 18 which is configured to receive the discharge fumes ( in particular , from the aforementioned expulsion system 16 ) ; a water introduction unit 20 arranged along the duct 18 and configured to introduce a defined quantity ( i . e . , a flow rate ) of water into said duct 18 so as to mix said de fined quantity of water with the discharge fumes and generate a discharge mixture ; and at least one heat exchanger 19 , which is placed downstream of the introduction unit 20 and in fluidic connection with the duct 18 to receive the discharge mixture , is configured to cool said discharge mixture so as to induce condensation of at least part ( in particular, of at least circa 50% ) of the water vapour contained in said discharge mixture so as to obtain condensate water ; and a collecting unit 21 to collect said condensate water AC ( schematically shown with droplets in Figure 4 ) . The addition of water in the discharge fumes advantageously allows to obtain a saturated discharge mixture , which can be cooled more easily, i . e . with a smaller heat exchanger 19 causing the condensation of much of the water contained in this discharge mixture .

According to some advantageous but non-limiting embodiments such as those shown in Figures 1 and 2 , the duct 18 extends from the aforementioned expulsion system 16 at least up to at least one heat exchanger 19 (in particular, up to a plurality of heat exchangers 19, as will be further described below) . According to some advantageous but nonlimiting embodiments, the water introduction unit 20 comprises (in particular, consists of) a water supply unit, for example a tank or a tap, and at least one nozzle (not visible in the appended figures) configured to spray the aforementioned defined quantity of water inside the duct 18 so as to mix it with the discharge fumes, having a first defined temperature, ranging from circa 85°C to circa 115°C , in particular from circa 80°C to circa 100°C, and to obtain a discharge mixture having a second defined temperature, lower than the first temperature, for example of circa 60°C. More specifically, advantageously but not limitatively, this second defined temperature is approximately equal to the dew temperature of the discharge mixture. Even more advantageously but not limitatively, the water introduction unit 20 is configured to introduce water into the duct 18 at a pressure of at least approximately 1 bar. In other words, as mentioned above, the water introduction unit 20 is configured to introduce a quantity of water into the duct 18 such to saturate (in use) the discharge fumes and obtain the above-mentioned discharge mixture.

The aforementioned saturated discharge mixture is thereby obtained, which is characterised by a much higher overall heat exchange coefficient than that of discharge fumes, which allows for a more efficient cooling of the discharge mixture resulting in easier (i.e. higher and/or faster) condensation of the water contained in such a discharge mixture, with the same heat exchange surface area.

According to some advantageous but non-limiting embodiments (such as, for example, the one schematically represented in Figure 2) , the recovery system 1 (in particular, the feeding system 5 ) comprises a heating device 34 , configured to heat the water suspension of ceramic material to a temperature of at least circa 70 ° C before introducing it into the spray-drying chamber 4 , taking advantage of part of the thermal energy of the aforementioned discharge fumes exiting the spray-dryer 2 . Thereby, the discharge fumes will undergo an initial cooling, yielding part of the thermal energy to the water suspension of ceramic material , with a consequent advantageous reduction in the quantity of water that the introduction unit 20 wil l have to introduce into the duct 18 to obtain the aforementioned saturated discharge mixture , and the water suspension of ceramic material , which once heated will be introduced into the spray-dryer 2 via the pumping assembly 9 ( as schematically shown in Figure 2 ) will be easier to atomi se .

In detail , according to certain embodiments such as that shown in Figure 2 , the heating device 34 is placed in fluidic connection : with the expul sion device 16 , for example via the duct 35 , to receive as input the discharge fumes exiting the spray-dryer 2 ; with the duct 18 , for example via the duct 36 , to feed the discharge fumes exiting said heating device 34 towards the aforementioned duct 18 ( in particular, upstream of the introduction unit 20 ) , and with the tank 8 , advantageously via the duct 37 , to receive the water suspension of ceramic material to be heated ( see Figure 2 ) .

More in detail , according to some advantageous but not limiting embodiments such as the one schematically shown in Figure 7 , the heating device 34 comprises ( in particular, consists of ) at least one heat exchanger 38 (more advantageously, a plurality of heat exchangers 38 arranged in series each) configured to heat said water suspension of ceramic material by structuring the thermal energy of the discharge gases .

Even more in detail , the ( i . e . each) heat exchanger 38 is placed in fluidic connection with the tank 8 to receive as input the water suspension of ceramic material having a temperature ranging from circa 30°C to circa 50°C, with the discharge system 16 to receive as input the discharge fumes exiting the spray-dryer 2 having a temperature varying from circa 80°C, in particular from circa 85°C, to circa 115°C, in particular, to circa 100°C, and with the duct 18 to feed the discharge fumes exiting from said heating device 34 (after yielding to the water suspension of ceramic material part of its thermal energy) at a temperature of 70°C (in particular, of circa 64°C) towards the aforementioned duct 18.

In detail, advantageously but not limitatively, the (i.e. each) heat exchanger 38 comprises (in particular, is) a coil exchanger. Even more advantageously but not limitatively, as in the non-limiting embodiment shown in Figure 7, the (i.e. each) heat exchanger 38 comprises (in particular, consists of) at least one heat exchange module 39 (in particular, a plurality of heat exchange modules 39 arranged in series with each other) , each one having: a housing 40 to receive and be flown through by the discharge fumes from the expulsion system 16, and a tube 41, advantageously but not limitatively finned, which extends within the housing 40, is in thermal connection with said housing 40 and is in fluidic connection with the tank 8 to receive and be flown through by the water suspension of ceramic material to be heated. Thus, in use, the water suspension of ceramic material, flowing along the tube 41, is heated by the flow of discharge fumes flowing through the housing 40 into which the tube 41 extends. Still in greater detail, the housing 40 comprises, in turn, an inlet 42 in communication with the duct 35 to receive the discharge fumes coming from the expulsion system 16 and an outlet 43 for expelling the cooled discharge fumes towards the duct 36 ( and from the latter to the duct 18 where , by means of the introduction of water, the above-mentioned discharge mixture is formed) and the tube 41 extends in said housing 40 so that the water suspension of ceramic material flowing through the tube 41 receives from the discharge fumes the heat necessary to pass from an initial temperature ranging from circa 30 ° C to circa 50 ° C to a final temperature of at least circa 70 ° .

As mentioned above , the recovery of water from the discharge mixture occurs , advantageously but not limitatively, by the passage of such a discharge mixture into at least one heat exchanger 19 . According to other advantageous but non-limiting embodiments , such as the one shown in Figure 2 , the recovery system 1 comprises a plurality of heat exchangers 19 , e . g . in the case shown three heat exchangers 19 , all similar to each other .

According to some advantageous but non-limiting embodiments , the ( i . e . each) heat exchanger 19 comprises ( in particular, is ) at least one shell and tube heat exchanger, intended to be flown through by a cooling fluid, advantageously but not limitatively water, so as to cool the discharge mixture and cause condensation of the aforementioned, at least part of the water vapour contained therein, on the walls of the shell and tube .

Even more advantageously but not limitatively, the ( i . e . each) heat exchanger 19 comprises at least one heat exchange module 22 having a housing 23 to receive the discharge mixture , a heat exchange tube 24 extending into the housing 23 and in thermal connection with said housing 23 and in fluidic connection with a cooling assembly 25 to receive and be flown through by the cooling fluid so as to cool the discharge mixture and cause condensation of the aforementioned at least part of the water vapour contained in the discharge mixture along an outer wall of said heat exchange tube 24 .

Advantageously but not limitatively, the ( i . e . each) heat exchanger 19 comprises a plurality of heat exchange modules 22 , advantageously but not limitatively arranged in series with each other, each having a housing 23 to receive the discharge mixture , and a heat exchange tube 24 in fluid connection with the cooling assembly 25 to receive and be flown through by the cooling fluid ( see Figures 3 and 4 ) . For example , in the case shown in Figure 3 , the water recovery system 1 comprises three heat exchangers 19 arranged side-by-side , each connected to the duct 18 to receive part of the discharge mixture and each of these heat exchangers 19 comprises , in turn, three heat exchange modules 22 , advantageously but not limitedly arranged in series with each other . Such a configuration makes it possible to reduce as much as possible the overall dimensions of the recovery system 1 ( in particular, of the heat exchanger 19 ) , while providing a heat exchange surface , advantageously but not limitedly provided by an outer wall of the heat exchange tube 24 , such as to ensure condensation of at least part of the water vapour contained in the aforementioned discharge mixture , in particular, as mentioned above at least circa 50 % of the water vapour .

According to some advantageous but non-limiting embodiments , such as those shown herein, the aforementioned cooling fluid is cooled by at least one cooling assembly 25 configured to feed the aforementioned cooling fluid to the ( in particular to each) heat exchanger 19 , in particular to the heat exchange tube 24 . According to some advantageous but non-limiting embodiments such as those shown in Figures 5 and 6 , the cooling assembly 25 comprises , in turn, at least one further heat exchanger 26 to contain the cooling fluid, which heat exchanger 26 is in thermal connection with a plurality of fans 27 configured to convey ambient air along a given path, advantageously around the heat exchanger 26, so as to cool the cooling fluid.

Referring in particular to Figures 1 and 2, even more advantageously but not limitatively, the recovery system 1 (in particular, the cooling assembly 25) comprises a supply duct 28 for feeding the cooling fluid (once cooled by said cooling coil 25) to the heat exchange tube 24 with a third temperature, in particular ranging from circa 26°C to circa 30°C; and a return duct 29 to receive the cooling fluid exiting the heat exchange tube 23, (thus after having cooled the discharge mixture) with a fourth temperature, which is greater than the third temperature, in particular ranging from circa 40°C to circa 50°C, and convey it to the cooling assembly 25. Even more advantageously but not limitatively, the recovery system 1 (in particular, the cooling assembly 25) comprises at least one pump 30 to pump the cooling fluid already cooled from the cooling assembly 25 to the heat exchange tube 24 (see, for example, Figures 1 and 2) .

Similarly to the what set forth above for the heat exchangers 19, according to some advantageous but nonlimiting embodiments, when the recovery system 1 comprises a plurality of heat exchangers 19 it also comprises a plurality (in particular the same number) of cooling assemblies 25; in particular, in this case, the recovery system 1 comprises a number of heat exchangers 19 similar to the number of cooling assemblies 25. In this case advantageously but not limitatively, each of the heat exchangers 19 is connected, in addition to the duct 18 to receive at least part of said discharge mixture, to a respective cooling assembly 25 to receive the aforementioned cooling fluid, advantageously at the aforementioned third defined temperature, and to cool the aforementioned discharge mixture by causing the condensation of at least part (in particular, at least circa 50%) of the water vapour contained in said at least part of the discharge mixture so as to obtain condensate water AC . In this case , advantageously but not limitatively, the collecting unit 21 is configured to collect the condensate water AC collected by each heat exchanger 19 .

Even more advantageously but not limitatively, the ( i . e . each) heat exchanger 19 comprises a guide surface (not shown in the accompanying figures ) configured to receive condensate water AC and guide it to an outlet tube 31 connecting the ( i . e . each) heat exchanger 19 to the collecting unit 21 .

According to some advantageous but non-limiting embodiments , this condensate water AC is then directed ( in a way known in itsel f ) towards the plant to form the aforementioned water suspension of ceramic material , in particular towards the raw material grinding mill where the aforementioned water suspension of ceramic material intended to be atomised is formed . This advantageously reduces water consumption considerably by allowing at least 50% of the water contained in this water suspension of ceramic material to be recovered during the spray-drying operation . Furthermore , this condensate water AC will have a temperature of at least circa 50 ° C, which advantageously allows it to be reused directly in the aforementioned mill to produce the water suspension of ceramic material without the need to heat it , with consequent advantages in terms of the environmental impact of the production plant .

Alternatively, or in combination, according to some advantageous but non-limiting embodiments ( such as the one schematically shown in Figure 1 ) , at least part of the aforementioned condensate water AC is used to heat the water suspension of ceramic material before feeding it into the spray-drying chamber 4 of the spray-dryer 2 .

More in detail , in this case , advantageously but not limitatively, the above-mentioned heating device 340 comprises ( in particular, consists of ) at least one spiral heat exchanger 44 ( schematically shown in Figure 8 ) placed in fluid connection with the collecting unit 21 to receive at least part of said condensate water AC having a temperature of at least about 50 ° C and with the tank 8 to receive as input the water suspension of ceramic material having a temperature ranging from circa 30 ° C and circa 50 ° C and heat it up to a temperature of at least circa 70 ° .

More in detail , advantageously but not limitatively, the spiral heat exchanger 44 , known in itsel f and only schematically and partially shown in Figure 8 , has two concentrically spiral circular chambers 45 , 46 ( i . e . channels ) : one chamber 45 (placed in fluidic connection with the collecting unit 21 and) intended to receive and be flown through from the periphery towards the centre by the condensate water AC and the other chamber 46 (placed in fluidic connection with the tank 8 and) intended to receive and be flown through from the centre towards the periphery by the water suspension of ceramic material to be heated . These concentric chambers 45 , 46 extend side by side and are thermally connected to each other so that the condensate water AC releases part of its thermal energy to the water suspension of ceramic material , causing it to heat up to a temperature of at least circa 70 ° C .

Advantageously, the adoption of such a type of heating device 340 , in particular the use of a spiral heat exchanger

44 , thanks to the fact that it causes , due to its shape , a spiral flow of the substances circulating in the two chambers

45 , 46 ( i . e . of the condensate water AC and the water suspension of ceramic material ) has a reduced risk of clogging compared to other types of heat exchangers . This spiral heat exchanger 44 compared to other types of heat exchangers is able to remove any deposits and/or material deposits on the walls of the chambers 45 , 46 . In fact , should the deposit of residues and/or the formation of fouling on the walls of one of the two chambers 45 , 46 of this spiral heat exchanger 44 occur, this would cause a partialisation of the section of the chamber 45 or 46 and consequently an increase in the speed of the flow of the substance within the spiral path defined by the chamber 45 or 46 itsel f , the increase in speed would cause a consequent increase in the turbulence of the flow which will cause an automatic elimination of any such fouling .

According to some advantageous but non-limiting embodiments , the recovery system 1 further comprises at least one outlet chimney 32 , arranged downstream of the heat exchanger 19 ( or of the plurality of heat exchangers 19 ) configured to allow the discharge fumes to be expelled to the external environment , once the liquid component within the ( or each) heat exchanger 19 has been separated by cooling and subsequent condensation of at least part of the water vapour, as described above . Even more advantageously but not limitatively, the recovery system 1 also comprises another safety chimney 33 arranged upstream of the heat exchanger 19 ( or of the plurality of heat exchangers 19 ) , even more advantageously upstream of the duct 18 , and configured to allow the discharge fumes to escape directly downstream of the spray-dryer 2 , in the event of mal functioning or maintenance in the remaining components of the recovery system 1 .

According to another aspect of the present invention, a water recovery method from a spray-dryer 2 is provided .

This method to recover water from a spray-dryer 2 comprises the following steps : a spray-drying step, during which a water suspension of ceramic material , advantageously of the type described above , is fed to a spray-dryer 2 , advantageously of a type known as described above in relation to the water recovery system 1 , which spray-dryer 2 atomises said water suspension of ceramic material and generates atomised ceramic powder and discharge fumes , advantageously of the type described above ; a conveying step, during which the discharge fumes are conveyed away from the spray-dryer 2 through at least one duct 18 to at least one heat exchanger 19 ; a water introduction step, ( at least partially) simultaneous with the conveying step, during which a defined quantity ( i . e . a flow rate ) of water is introduced into the duct 18 so as to mix with the discharge fumes and generate a discharge mixture ; a water recovery step, during which said discharge mixture flows through the aforementioned heat exchanger 19 and said heat exchanger 19 cools the discharge mixture so as to cause condensation of at least part ( in particular, of at least circa 50% ) of the water vapour contained in the discharge mixture so as to obtain condensate water AC ; and a collecting step, during which said condensate water AC is collected in a collecting unit 21 .

Advantageously but not limitatively, during said spraydrying step, discharge fumes are generated with a first defined temperature ranging from circa 80 °C ( in particular, circa 85 ° C ) to circa 115 ° C ( in particular, circa 100 ° C ) .

Advantageously but not limitatively, as mentioned above for the recovery system 1 , the method to recover water from a spray-dryer 2 comprises a reuse step wherein the condensate water AC is reused to form a water suspension of ceramic material to be atomised, with considerable environmental benefits in terms of resource savings . Alternatively or additionally, this condensate water AC is reused to heat the water suspension of ceramic material to a temperature of at least circa 70 ° C, by using a heating device 340 , as already explained above in relation to the recovery system 1 . This advantageously facilitates the spray-drying step .

Advantageously, but not limitatively, the aforementioned water introduction step involves spraying the aforementioned defined quantity of pressurised water into the duct 18 in order to mix with the discharge fumes and generate a discharge mixture .

Even more advantageously but not limitatively, the water introduction step comprises a saturation sub-step, during which the aforementioned defined quantity of water is mixed with the discharge fumes , having a first defined temperature , advantageously ranging from circa 80 ° C to circa 100 ° C, so as to obtain an discharge mixture having a second defined temperature , lower than the first temperature , in particular, equal to circa 60 ° C . More particularly, advantageously but not limitatively, said second defined temperature is approximately equal to the dew temperature of said discharge mixture . In other words , a quantity of water is added in this saturation sub-step such to ensure saturation of the discharge fumes and to obtain a saturated discharge mixture . This surpris ingly allows an easier recovery of water from the discharge mixture , facilitating the cooling of the discharge mixture , which is thus characterised by a much higher overall heat exchange coef ficient than that characteri sing the discharge fumes , which allows a more ef ficient cooling of the discharge mixture resulting in an easier ( i . e . higher and/or faster ) condensation of the water contained in such a discharge mixture , with the same heat exchange surface area .

According to some advantageous but non-limiting embodiments , the above-mentioned water recovery step comprises : a feeding sub-step, during which the discharge mixture is conveyed towards a housing 23 of the heat exchanger 19 ( in particular, of the heat exchange module 2 ) , which housing 23 is in thermal connection with a heat exchange tube 24 ; a cooling sub-step, which is ( at least partially) simultaneous with the feeding step, during which the aforementioned cooling fluid, having a third defined temperature , in particular ranging from circa 26 ° C to circa 30 ° C, is conveyed, advantageously but not limitatively via the aforementioned supply duct 28 , from the cooling assembly 25 to the heat exchange tube 24 to cool the discharge mixture ; and an outlet sub-step, during which the cooling fluid, after having cooled the discharge mixture and having assumed a fourth defined temperature , which is greater than the third defined temperature , for example ranging from circa 40 ° C to circa 50 ° C, is conveyed, advantageously but not limitatively via the aforementioned return duct 29 , out of the heat exchanger 19 towards the cooling assembly 25 .

According to still other advantageous but non-limiting embodiments , the water recovery method comprises a cooling step of the cooling fluid, during which the cooling assembly 25 , advantageously made as described above , cools the cooling fluid from the above-mentioned fourth temperature to the above-mentioned third temperature .

Advantageously but not limitatively, the water recovery method also comprises a filtering step, ( at least partially) following the spray-drying step and ( at least partially) preceding the conveying step, during which the discharge fumes exiting the spray-dryer 2 are filtered before reaching the duct 18 to separate any residual ceramic material from the discharge fumes . Advantageously but not limitatively, this filtering step is carried out by means of the above- mentioned filtering and/or abatement devices 17 , for example by means of a bag filter 17 ( known in itsel f and not further described herein) , as schematically shown in Figures 1 and 2 , or by means of one or more separating cyclones ( known in themselves and not further described herein) .

Alternatively or additionally, advantageously but not limitatively, the water recovery method comprises a heating step, ( at least partially) preceding the spray-drying step ( in particular, at least partially simultaneous with the introduction sub-step ) during which a heating device 34 , 340 heats the water suspension of ceramic material to a temperature of at least circa 70 ° C before feeding it to the spray-dryer 2 .

As already explained in relation to the recovery system 1 , in this case , according to some advantageous but nonlimiting embodiments such as , for example , the one shown in Figure 2 , the heating step comprises a first feeding substep, during which at least part o f the discharge fumes from the spray-dryer 2 is fed to a heat exchanger 38 ( advantageously but not limitatively implemented as mentioned above in relation to the recovery system 1 ) which is part of the heating device 34 , advantageously but not limitatively via the duct 36 ; a second feeding sub-step, during which the water suspension of ceramic material is fed to said heat exchanger 38 , advantageously but not limitatively via the duct 37 ; a heating sub-step, during which the discharge fumes , through said heat exchanger 38 , trans fer part of their thermal energy to the water suspension of ceramic material and heat it up to a temperature of at least circa 70 ° C ; a first exit sub-step, ( at least partially) preceding the water introduction step, during which the cooled discharge fumes exiting the heat exchanger 38 are fed to the duct 18 , advantageously via the duct 36 ; and a second exit sub-step, during which the heated water suspension of ceramic material is fed as input to the spray-dryer 2 .

According to stil l other advantageous but non-limiting embodiments , the water recovery method also comprises a discharge step, ( at least partially) subsequent to the water recovery step, during which the discharge mixture , after being cooled by the heat exchanger 19 , advantageously but not limitatively via the aforementioned discharge chimney 32 . Advantageously but not limitatively, the spray-drying step comprises : an introduction sub-step, during which a feeding system 5 ( advantageously of the type described above in relation to the recovery system 1 ) feeds j ets of a water suspension of ceramic material at high pressure into a spraydrying chamber 4 ( advantageously of the type described above in relation to the recovery system 1 ) ; and a drying substep, during which a distribution device 7 ( advantageously of the type described above in relation to the recovery system 1 ) distributes a flow of hot air inside the spraydrying chamber 4 and this flow of hot air hits the j ets of water suspension of ceramic material generating the aforementioned atomised ceramic powder AP and the aforementioned discharge fumes .

The recovery method and the recovery system 1 of the present invention have several advantages , including the following .

The recovery system 1 and the recovery method of the present invention make it possible to recover a large part of the water used to form the water suspension of ceramic material that is processed in the spray-dryer 2 , with obvious advantages in terms of environmental and economic impact .

Furthermore , the recovery method and recovery system 1 of the present invention make it possible to recover such water at a temperature of at least circa 50 ° C, which makes it possible to reuse such condensate water AC directly in the mill to produce the water suspension of ceramic material without the need to heat it , with consequent advantages in terms of the environmental impact of the production plant .

Furthermore , the fact that recovery system 1 is modular, i . e . it can comprise a variable number of heat exchangers 19 makes it possible to easily adapt it to any spray-dryer 2 of a known type , regardless of its si ze by simply adapting the number of heat exchangers 19 of the recovery system 1 accordingly. This makes the recovery system 1 suitable for use with any one of the commercial spray-dryers of the same Applicant known by the names ATM090, ATM006, ATM012, ATM018, ATM036. ATM052, ATM065, ATM110, ATM140, ATM180, ATM200 and ATM250.